Key to Ooctonus species in the Neotropical region. Females.

1 Propodeum with median areole almost touching dorsellum, with extremely short and thick carinae (Figs 13, 14); clava without bullae (Figs 8, 9).................................................................... O. costaricensis, sp. n.

- Propodeum with median areole clearly separated from dorsellum by a median carina (Figs 15–17); clava with at least one group of at least 2 bullae (Figs 7, 10, 11)................................................................... 2

2(1) Flagellum with fl5 and fl6 both without mps (Fig. 10); clava with bullae in 3 usually distinctly separate groups (Fig. 10), though apical two groups sometimes close together................................................... O. woolleyi, sp. n.

- Flagellum with at least 1 mps on at least one of fl5 and fl6 or if exceptionally both without mps then clava with at most two groups of bullae (Fig. 7)................................................................................ 3

3(2) Flagellum with 2 mps on each of fl5 and fl6 (Fig. 11); clava at least 244 µm and with one group of 2 bullae just beyond middle of clava (Fig. 11)..................................................................... O. zolnerowichi, sp. n.

- Flagellum with fewer mps on fl5 and fl6, either 2 and 1, 1 and 1, or 1 and 0 mps (Fig. 7); clava shorter, at most 230 µm, and with two groups of at least 3 bullae (usually more) beyond middle and near apex (Fig. 7)................... O. clebschi, sp. n.